[Bug libc/12587] sysconf(_SC_*CACHE) returns 0 for all caches on some CPUs.

["john.haxby at oracle dot com" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=12587

John Haxby <john.haxby at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

--- Comment #15 from John Haxby <john.haxby at oracle dot com> 2011-04-06 12:20:32 UTC ---
(In reply to comment #14)
> None of that means at all that a maximum function number >= 4 implies that
> caches are guaranteed to be reported in leaf 4.  Why are you wasting my time if
> you have nothing to show but completely irrelevant data?  The current code
> works and unless Intel really screws up is guaranteed to work.

I'm sorry, Ulrich, but "Software can enumerate the deterministic cache
parameters for each level of the cache hierarchy[...]" means exactly that; it
does not mean that only some cache parameters are enumerated, now or in the
future.  I know that you can spot ambiguity where I cannot (I have seen the
evidence of that in the past, but I do not believe that you have seen something
that the rest of us have missed this time.)

It does mean, however, that some current or planned CPU that does not have its
cache parameters described by the intel_02_known[] table will fail whereas use
of cpuid-4 will continue to work.

However, if you would prefer to check the intel_02_known[] table for each new
cpu that Intel produce that it your choice, but personally I would prefer to
fix this problem just once.

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